Mononuclear ruthenium(II) complexes bearing the (S,S)-iPr-pybox ligand

The complexes trans-[RuCl2(L){(S,S)-iPr-pybox}] ((S,S)-iPr-pybox = 2,6-bis[4′-(S)-isopropyloxazolin-2′-yl]pyridine, L = PMe3 (1), P(OMe)3 (2), PPh2(CH2CHdouble bond; length as m-dashCH2) (3), CNBn (5), CNCy (6) and MeCN (7)) have been synthesized by substitution of ethylene on the precursor trans-[RuCl2(η2-C2H4){(S,S)-iPr-pybox}]. This complex also reacts with cyclooctadiene (cod) or norbornadiene (nbd) and NaPF6, in refluxing methanol, giving the coordination compounds [RuCl(η4-cod){(S,S)-iPr-pybox}][PF6] (8) and [RuCl(η4-nbd){(S,S)-iPr-pybox}][PF6] (9). The structures of complexes [RuCl(CO)(PPh3)(H-pybox)][BF4] (H-pybox = 2,6-bis(dihydrooxazolin-2′-yl)pyridine) (4), 6 and 8, have been resolved by X-ray diffraction methods. The catalytic activity of the new complexes in transfer hydrogenation of acetophenone has also been examined.